Effect of 3 MeV Fe11+ ions pre-damage on blistering and deuterium retention in two tungsten grades

Abstract

Abstract The effects of 3 MeV Fe11+ ions pre-damage on blistering and deuterium (D) retention in two types of tungsten, polycrystalline hot-rolled bulk tungsten (W) and recrystallized tungsten (rec-W) exposed to D plasma have been investigated. Two kinds of blisters can be distinguished at the surface of undamaged W. One is intra-granular blisters with the size of ~0.2–1.5 μm, and the other is inter-granular blisters with the size of ~15–22 μm. Only intra-granular blisters are observed at the surface of undamaged rec-W. Compared to the undamaged W, the size of blisters in the damaged W increases, while the density of blisters decreases. However, there are no blisters at the surface of damaged rec-W. For both W and rec-W, Fe11+ ions pre-damage can effectively inhibit the formation of intra-granular blisters. The grain boundaries close and parallel to the sample surface play an important role for the formation of inter-granular blisters. Fe11+ ions irradiation introduces a large number of defects such as dislocation loops and nano-scale voids in W and rec-W samples. The total D retention in W and rec-W increases significantly due to the Fe11+ ions irradiation and tends to be saturated at around 0.3 dpa. In contrast, the total D retention in the undamaged W is higher than that in the undamaged rec-W, but it is quite comparable in the damaged W and rec-W samples.